Not doing something because 'google might do it' is not a very good reason.
There are reasons this hasn't been done before. I don't think it's a viable startup idea. Think about the capital you would need to even get something like this off the ground. Doing the AI API 'right' would require a supercomputer, if you take it far enough.
A guy can dream though. Maybe doing high-frequency trading would get you most of the way there.
IMHO, go for the niche: elsewhere in this thread Directed Edge was mentioned, and they are a good example of a business tackling a well-defined problem with exciting tools and techniques.
by implementing a web app that anyone could use (mobile or not), i also envisioned a sort of community/market place where people could post their data and do simple stuff and/or have experts try to tackle it for a service fee. and whatever algorithms came out of that would be made available for future data that has similar features. i recently came across a similar site. can't remember the name.
anyway, i know this is not necessarily a viable startup idea. and if it is, it's ultimately all about execution. i'm still dreaming though and was psyched google launched their predict api.